Spiders Evolved Spare Legs

Arachnids missing up to two limbs can build webs and hunt with ease.

Scientists may have uncovered why spiders are so creepy-crawly—they have more legs than they need, a new study says.

After collecting thousands of female spiders in the wild, scientists found that more than 10 percent of the arachnids were missing at least one of their eight legs.

"We wondered if this was handicapping them in any way," said study co-author Alain Pasquet at the University of Nancy 1 in France.

The research team placed 123 Zygiella x-notata spiders in individual plastic boxes, where the animals could build webs. Sixty of the spiders were eight-legged, while 63 were each missing one or more legs. (See spider-web pictures.)

Pasquet and his colleagues found that webs built by spiders missing at least one leg did not differ much from the webs built by spiders that were intact.